rear differential cover swap while on car?

Buffman · Post by **Buffman** » Tue Sep 01, 2009 6:39 am

Apparently I tightened the new diff drain plug a little too tight (had teflon tape on it dohH!) and actually cracked the differential housing. I seem to have a leak now, even though the crack wasn't very big and didn't seem to extend into the cover very much. I did silicone the hell out of the plug after doing this and let it sit. No dice still seems to be leaking.

I'm used to traditional RWD cars that have it easy to remove the diff cover. Not used to this IRS. So my question is, is it possible to swap the differential cover without dropping the whole rear and or center section? Or am I going to have to?

n2x4 · Post by **n2x4** » Tue Sep 01, 2009 2:19 pm

I've never changed a diff cover while in a car, but I could see it to be possible. Wouldn't be easy though!

The problem is that the differential mounts are built into the cover:

Since these mounds are in the subframe, you'll need to get the studs out of the cover, and then unbolt the 9 bolts that mate the cover to the diff. You could probably loosen all the mounting bolts and get the diff to droop enough to work in there.

When switching covers, be aware that not all covers are interchangeable. You can see the two diffs pictured don't mount up the same.

Buffman · Post by **Buffman** » Tue Sep 01, 2009 4:42 pm

gotcha.

from looking, I can phyiscally get to 8 of the 9 cover bolts. As long as the stud nuts come off, I should be able to use the jamb nut technique to remove the studs. I could remove that little bushing assembly for more room. Guess time to find a spare cover.

kimokalihi · Post by **kimokalihi** » Tue Sep 01, 2009 4:45 pm

Those diff covers look like they're shaped a bit differently and one has heat sinks but other than that it looks like the bolt/stud placement and oil check and drain holes are identical.

n2x4 · Post by **n2x4** » Tue Sep 01, 2009 7:22 pm

kimokalihi wrote:Those diff covers look like they're shaped a bit differently and one has heat sinks but other than that it looks like the bolt/stud placement and oil check and drain holes are identical.

The dirty diff is from a 95 Impreza, the other is a LSD Legacy diff. What you can't tell from that picture, is that the diff cover actually protrudes out further on the heat sinked diff to fit a revised diff mount on the subframe. Here's a pic of the bolts used between the two diff covers. You can see they're very different in length. Top stud is from the legacy diff, bottom from the Impreza:

One other thing that you'll need to watch for when removing the cover is that the gears are not flush with the case surface, so you can't slide it straight down. That's why the cover isn't flat, it's got a curve to clear the gears inside. Hopefully that makes sense...

Buffman · Post by **Buffman** » Tue Sep 01, 2009 10:38 pm

yeah like traditional rwd covers. Guess I will have to see how much clearance there is in addtion to what I'm removing.

Buffman · Post by **Buffman** » Wed Sep 02, 2009 12:36 am

I guess another question is, if I want to drop the center section, so I have to pull the knuckles to pull the CV shafts, or can I pull the center section without having to dick around with the CV shafts (besides knocking the roll pin out)? IIRC I saw pics from Josh when he swapped his center section out, and it appears he didn't have to remove the half shafts?

Thanks

mexicanzero · Post by **mexicanzero** » Wed Sep 02, 2009 1:51 am

when i did my gas tank i had to drop the diff and the crossmember the way i did the diff was i unbolted everything and lowered it about a foot i think so just enough that it was clear of the crossmember completely so that i could remove it and i never touched the cv shafts. as long as you dont lower it too much and rest it on soemthing, dont leave it hanging, they wont pop out of place

hah i actually have a pic too! i've never posted pics on here though so i dont know how. but i could email it to you if you're interested...
-Alex

Buffman · Post by **Buffman** » Wed Sep 02, 2009 5:57 am

you can upload them on www.imageshack.us and use the direct link and put [img] [./img] remove the . around the link

mexicanzero · Post by **mexicanzero** » Thu Sep 03, 2009 1:28 am

mexicanzero · Post by **mexicanzero** » Thu Sep 03, 2009 1:30 am

wow that was easy i always though it was a complicated process
thanks! hope the pics help

Buffman · Post by **Buffman** » Thu Sep 03, 2009 2:05 am

definately. If that can be done, I feel a little easier about doing this. Thanks

Post by **Legacy777** » Thu Sep 03, 2009 6:19 pm

I'd highly recommend lowering/removing the diff.

I removed the diff the same way as above without removing the cv axles from the hubs. I loosened/removed the long bolt that attaches the lateral links to the hub to give me some room.

legacycentral bbs

A forum for 89-94 BC-BF(BJ) Legacy Owners and Fans

rear differential cover swap while on car?

rear differential cover swap while on car?